This invention relates generally to surface acoustic wave (SAW) devices and, more specifically, to a need in SAW devices for processing large amounts of parallel information.
SAW devices employ substrates of a piezoelectric material, across which elastic surface waves are propagated between sets of electro-acoustic transducers disposed on the substrate surface. The surface waves, called Rayleigh waves, have an amplitude of displacement that is largest right at the substrate surface. In a piezoelectric material, deformations induced by the waves induce local electric fields, which are propagated with the acoustic waves and extend into space above the surface of the material. These electric fields will interact with electrodes disposed on the surface of the material, to serve as electrical input and output transducers for the surface acoustic wave device.
Although many SAW devices are basically serial in nature, and process signals from an input transducer to a single output transducer, there are other classes of SAW devices in which output information is generated in parallel, such as in spectrum analyzers, chirp analyzers, or acoustooptic Bragg cells. Because of the large number of simultaneous parallel outputs involved, these signals are very difficult to process and to extract useful information from.
It will be appreciated from this brief explanation that there is a need for a SAW device that can convert many parallel channels into a serial format. This would facilitate further digital processing of the signals. The present invention provides a solution to this problem.